The present invention relates to solutions containing compositions useful in the fixation of cells and tissues for histological study and to methods for the fixation of cells and tissues using as the fixing agents certain compounds.
The objective of tissue fixation is to provide as much detail of the cell as possible. To do this, it is necessary to maintain the cells in their original unaltered morphology so that maximum cellular detail is observed under the microscope. With the development of immunostaining there is also the requirement that the antigens of the cells are not altered by the method of fixation or stabilization. Although the microscope is the usual means for examining cells that are fixed and stained, they may also be examined by the laser or the flow cytometer. The flow cytometer is an important device for examining a large number of cells in a brief time.
The usual formulations for stabilization of cells contain one or more agents which react vigorously with the proteins of the cells to denature, coagulate and insolubilize the components of the cell. Typical of this type of agent is formaldehyde, picric acid, mercuric ions and glutaraldehyde. In addition, some less toxic compounds which can also denature and stabilize the proteins are acetic and formic acid, but these are often less suitable for a number of histological procedures.
Unfortunately, the toxicity associated with most of the compounds commonly used in histological techniques renders their use less than satisfactory. For example, formaldehyde, the most common of these fixatives, is a noxious gas which is also toxic, flammable and carcinogenic. Although efforts are made when this chemical is used to protect workers and avoid contamination of the drainage system when disposed, these efforts are usually both expensive and inconvenient, and fixatives such as formaldehyde still present a danger to laboratory workers and health care professionals. It is thus highly desirable to develop fixatives which can be used safely, effectively and conveniently in histological studies.